The PRXamide Neuropeptide Signalling System: Conserved in Animals

The PRXamide family of neuropeptides is based on the core amino acids at the C-terminal end that are required for activity and on sequence homology of their cell-surface G protein-coupled receptors. The PRXamide family of neuropeptides includes the pyrokinins, pheromone biosynthesis-activating neuropeptides, diapause hormone, CAPA/periviscerokinins (aka cardioacceleratory peptide 2b), and ecdysis-triggering hormone found throughout the Insecta. The vertebrate homologues include neuromedin U because it has a PRNamide C-terminal sequence. The vertebrate G protein-coupled receptors that are homologous to the insect receptors also include receptors for ghrelin, motilin, and thyrotropin-releasing hormone in addition to the neuromedin U receptor. This review will not only summarize the recent literature on this neuropeptide family but also include recent information about the prevalence of the neuropeptides across the Insecta based primarily on genomic and transcriptomic sequence information. Information is also included about the PRXamide ligands and their receptors in other protostome and deuterostome lineages. The conservation of ligands and receptors among all animals will be presented along with ideas on the coevolution of ligands and receptors. The first four pages of this chapter are available